For various applications, e.g. detecting a rotation position, rotating bodies are required, which can be mounted e.g. torque proof on a shaft stub, on whose outer circumference defined circumferential portions with alternating magnetization, thus north and south poles are applied.
Thus, for stability reasons, the core, namely the hub of the rotating body, typically has to be made of a metal material, in particular steel, while the magnetizations are caused in a magnet ring mounted thereon, which is made of a magnetizable material, e.g. ferrite or bonded neodymium iron boron.
Since such rotation body with its magnetized surface, mostly the circumferential surface, has to be moved along a magnetic field sensor with a small distance there between, which magnetic field sensor is mounted in a stationary position next to the rotating body, the rotating body also has to comply with high precision requirements with respect to roundness and axis alignment, in order to reliably prevent touching the magnet ring and the magnet field sensor.
Depending on the application, however, due to large temperature variations and the ensuing different expansion properties of the magnetic ring on one side and the hub material on the other side, high tensions can be generated there between, so that a fracture of the magnet ring and thus a destruction of the rotating body can occur.
Furthermore, when a magnet ring is glued onto the hub, the precision requirement for the rotating body often necessitates additional machining after the gluing process, in order to comply with the roundness requirements for the rotating body.